我正在尝试使用 ISampleGrabberCB::BufferCB
使用以下代码将当前帧转换为位图:
int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength)
{
try
{
Form1 form1 = new Form1("", "", "");
if (pictureReady == null)
{
Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length");
}
Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer");
Bitmap bitmapOfCurrentFrame = new Bitmap(width, height, capturePitch, PixelFormat.Format24bppRgb, buffer);
MessageBox.Show("Works");
form1.changepicturebox3(bitmapOfCurrentFrame);
pictureReady.Set();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
return 0;
}
但是这似乎不起作用。
此外,当我按下运行以下代码的按钮时,它似乎会调用此函数:
public IntPtr getFrame()
{
int hr;
try
{
pictureReady.Reset();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight);
try
{
gotFrame = true;
if (videoControl != null)
{
hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger);
DsError.ThrowExceptionForHR(hr);
}
if (!pictureReady.WaitOne(9000, false))
{
throw new Exception("Timeout waiting to get picture");
}
}
catch
{
Marshal.FreeCoTaskMem(imageBuffer);
imageBuffer = IntPtr.Zero;
}
return imageBuffer;
}
运行此代码后,我会收到一个显示“Works”的消息框,这意味着我的 BufferCB
必须被调用,但不会用当前图像更新我的图片框。
BufferCB
不是在每个新帧之后调用吗?如果是这样,为什么我没有收到“Works”消息框?
最后,是否有可能使用 BufferCB
将每个新帧转换为位图(这用于以后的处理),如果可以,如何实现?
编辑后的代码:
int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength)
{
Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length");
Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer");
CopyMemory(imageBuffer, buffer, bufferLength);
Decode(buffer);
return 0;
}
public Image Decode(IntPtr imageData)
{
var bitmap = new Bitmap(width, height, pitch, PixelFormat.Format24bppRgb, imageBuffer);
bitmap.RotateFlip(RotateFlipType.RotateNoneFlipY);
Form1 form1 = new Form1("", "", "");
form1.changepicturebox3(bitmap);
bitmap.Save("C:\\Users\\...\\Desktop\\A2 Project\\barcode.jpg");
return bitmap;
}
按钮代码:
public void getFrameFromWebcam()
{
if (iPtr != IntPtr.Zero)
{
Marshal.FreeCoTaskMem(iPtr);
iPtr = IntPtr.Zero;
}
//Get Image
iPtr = sampleGrabberCallBack.getFrame();
Bitmap bitmapOfFrame = new Bitmap(sampleGrabberCallBack.width, sampleGrabberCallBack.height, sampleGrabberCallBack.capturePitch, PixelFormat.Format24bppRgb, iPtr);
bitmapOfFrame.RotateFlip(RotateFlipType.RotateNoneFlipY);
barcodeReader(bitmapOfFrame);
}
public IntPtr getFrame()
{
int hr;
try
{
pictureReady.Reset();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight);
try
{
gotFrame = true;
if (videoControl != null)
{
hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger);
DsError.ThrowExceptionForHR(hr);
}
if (!pictureReady.WaitOne(9000, false))
{
throw new Exception("Timeout waiting to get picture");
}
}
catch
{
Marshal.FreeCoTaskMem(imageBuffer);
imageBuffer = IntPtr.Zero;
}
return imageBuffer;
}
我还需要按下按钮来运行 BufferCB
感谢阅读。
最佳答案
BufferCB
为相机捕获的每个新帧调用。您看不到消息框,因为该方法是从另一个线程(不是 ui 线程)调用的。参见 this question了解详情。
在我的代码中,我使用 AutoResetEvent
来捕获帧:
#region samplegrabber
/// <summary>
/// buffer callback, COULD BE FROM FOREIGN THREAD.
/// </summary>
int ISampleGrabberCB.BufferCB (double sampleTime,
IntPtr pBuffer,
int bufferLen)
{
if (_sampleRequest)
{
_sampleRequest = false;
if (bufferLen > _bufferSize)
throw new Exception ("buffer is wrong size");
Win32.CopyMemory (_buffer, pBuffer, _bufferSize);
// Picture is ready.
_resetEvent.Set ();
}
else
_dropped++;
return 0;
}
然后可以使用另一个函数从 IntPtr
解码图像:
public Image Decode (IntPtr data)
{
var bitmap = new Bitmap (_width, _height, _stride, PixelFormat.Format24bppRgb, data);
bitmap.RotateFlip (RotateFlipType.RotateNoneFlipY);
return bitmap;
}
关于c# - 如何将 ISampleGrabber::BufferCB 的缓冲区转换为位图,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19622345/